Conflict of interest concerns have been raised about two board members of federal government bodies involved in the consideration of a billion-dollar loan to Indian mining giant Adani.

Adani is seeking the loan from the Northern Australia Infrastructure Facility (NAIF) for a rail line linking its proposed Carmichael coal mine to the port of Abbot Point in north Queensland.

Green group Environmental Justice Australia said the two board members had connections to Queensland mining companies that could benefit financially if the Adani mine is approved and as such have a potential conflict of interest.

They have written to the NAIF and to the Export Finance and Insurance Corporation (Efic), the government credit agency, which is helping to evaluate the loan.

Environmental Justice Australia said Annabelle Chaplain was a board member of Efic but also a director of Downer EDI, which has a $2 billion commercial arrangement with Adani.

It also said Karla Way-McPhail was a NAIF board member as well as being the chief executive of two companies that do work in the mining industry.

One is Undamine Industries, which hires out labour and machinery to support mining operations.

The second is Coal Train Australia, a mining training company based in central Queensland.

Efic board member Ms Chaplain is listed as an independent non-executive director of Downer EDI, whose $2 billion arrangement is to conduct drilling, blasting and coal haulage at the Carmichael Mine, if it goes ahead.

According to Downer EDI's last annual report, Ms Chaplain held 74,000 shares in the company, putting her stake at more than $450,000.

Downer EDI chief executive Grant Fenn told The Australian Financial Review last year the company was a "supporter" of the Adani mine and that the Indian giant was "a very large potential customer".

'Clear connections' to companies that could gain from loan

Environmental Justice Australia said both Ms Way-McPhail and Ms Chaplain had clear connections to companies that could benefit financially if the Adani project was approved.

"We understand NAIF is considering proposals by an [Adani company] and Aurizon Holdings Ltd for Galilee Basin rail projects that would cart thermal coal to the Great Barrier Reef Coast," Environmental Justice Australia wrote in its letter to both government bodies.

"There is a perception that Ms Way-McPhail could gain an advantage if either project were to proceed."

Efic told the ABC Ms Chaplain was unavailable for interview.

"In response to your questions, Efic is a corporate Commonwealth entity under the provisions of the Public Governance, Performance and Accountability Act 2013 (PGPA Act)," it said.

"Section 29 of the PGPA Act requires that all directors of Efic are required to disclose where they have a material personal interest that relates to the affairs of Efic.

"We can confirm that directors of the Efic board are aware of their obligations in this regard."

The NAIF said Ms Way-McPhail was also unavailable for comment.

In a statement, it said its directors "are aware of their obligations regarding disclosures of conflicts of interest as required under the Public Governance, Performance and Accountability Act 2013, as well as their obligations to comply with the NAIF's conflict of interest policy which is available on the NAIF website".

David Barnden from Environmental Justice Australia said both the NAIF and Efic had failed to answer questions about whether the two members were recusing themselves from discussions and decisions about Adani.

"It is important because taxpayers don't necessarily have a choice of how their money is being spent or being put at risk, so the officials of government organisations are in a very, very privileged position dealing with such large amounts of taxpayers money and they should be held to a very, very high standard of disclosure and transparency," Mr Barnden said.

The NAIF has been accused of excessive secrecy over the operation of its board and the board's deliberations.

The ABC reported earlier this year the NAIF rejected a freedom of information request for the dates and locations of its upcoming board meetings.

The NAIF chief executive said the "disclosure of the dates of board meetings could reasonably be expected to adversely affect the NAIF's operations" by creating media attention and protest activity.